30 THE GEOLOGICAL HISTORY OF THE HORSE. 
those who will examine the evidence of facts, upon which the 
conclusions rest, there can remain no more reasonable doubt of the 
truth of what I have been relating than is felt by the antiquary 
who, finding the catacombs of Egypt stored with the mummies of 
men, apes, and crocodiles, concludes them to be the remains of 
mammalia and reptiles that have formed part of an ancient popu- 
lation on the banks of the Nile. 
Now, if it was a sudden catastrophe or deluge which destroyed 
the hippotamus, the tiger, and the elephant, how did the ox, deer, 
and horse continue to escape the flood of waters] Why this par- 
tial selection of its victims among the ancient inhabitants of our 
country] But these changes on our island are not more wonderful 
than the mutations that have occurred in other parts of the world. 
It is almost impossible to reflect without the deepest astonishment 
on the changes that have taken place on the continent of South 
America. Formerly it must have swarmed with great monsters, 
like the southern parts of Africa; but we now find only the tapir, 
guanaco, armadillo, and capybara — mere pigmies compared to the 
antecedent races. The greatest number, if not all, lived at the 
epoch we have been describing, and many of them were contem- 
poraries of the existing mollusca. 
“ In the Pampas,” says Darwin, “ the great sepulchre of such 
remains, there are no signs of violence, but, on the contrary, of the 
most quiet and scarcely-sensible changes.” “ What shall we say,” 
he continues, “of the death of the now fossil horse ] Did those plains 
fail in [pasture, which afterwards were overrun by thousands and 
tens of thousands of the successors of the fresh stock introduced 
with the Spanish colonist]” “ One is tempted,” he continues, “ to 
believe in such simple relations as variations of climate and food, or 
introduction of enemies, or the increased number of other species, 
as the cause of the succession of races. But it may be asked, 
whether it is probable that any such cause could have been in 
action during the same epoch over the whole northern hemisphere, 
so as to destroy the elephas primogenus on the shores of Spain, on 
the plains of Siberia, and in Northern America; and, in like man- 
ner, the bos urus, over a range of scarcely less extent] Did such 
changes put a period to the life of the mastodon augustidens and of 
the horse, both in Europe and on the eastern slope of the Cor- 
dillera in southern America] If they did, they must have been 
changes common to the whole world; such as a gradual refrige- 
ration, whether from modification of physical geography, or from 
central cooling. But in this assumption we have to struggle with 
the difficulty that these supposed changes, although scarcely suffi- 
cient to affect molluscous animals either in Europe or South Ame- 
rica, yet destroyed many quadrupeds in regions now characterised 
